1. Field of the Invention
The present invention relates to an actuator support structure that supports an actuator which flexurally vibrates and a pump device that includes the actuator support structure and conveys fluid.
2. Description of the Related Art
A thin pump device has been developed which is used for conveying air for a fuel cell system and other devices, and controls the flow of fluid by using an actuator that flexurally vibrates (e.g., see International Publication No. 2008/069264).
FIG. 1 is a diagram illustrating an example of an existing pump device and its action.
The pump device 100 includes an actuator 110 including a vibration plate 111 and a piezoelectric element 112 and an opposed plate 101 disposed so as to be adjacent to and opposed to the vibration plate 111. The vibration plate 111 is made of metal and fixed at the entire outer peripheral portion thereof to the opposed plate 101. The piezoelectric element 112 is attached to a center portion of the vibration plate 111. The opposed plate 101 includes a first opening 102 disposed at a position that faces the center of the actuator 110 and a second opening 103 disposed at a position that faces the actuator 110 so as to be positioned outward of the piezoelectric element 112. In this pump device, when a voltage of a predetermined frequency is applied to the piezoelectric element 112, the vibration plate 111 resonates in a third-order resonance mode, and in the vibration plate 111, a portion that faces the first opening 102 and a portion that faces the second opening 103 bend in opposite directions. By repeating this bending, the pump device 100 sucks fluid through one of the first opening 102 and the second opening 103 and discharges the fluid through the other of the first opening 102 and the second opening 103.
There is demand for the size of an electronic apparatus in which a pump device is included to be reduced in size, and for the size of the pump device to be reduced without reducing the pumping power (fluid pressure and flow rate). In addition, for the electronic apparatus, a decrease in a power-supply voltage is also demanded, and for the pump device, a decrease in a drive voltage is also demanded. However, the pumping power of the pump device tends to decrease as the size is reduced or the drive voltage is decreased. Thus, there are limits to the size reduction and the drive voltage decrease.